Outcomes in Pediatric Vestibular Loss In children with cochlear implants (CCI), the presence of vestibular loss may result in gross motor developmental delay and reduced visual acuity, requiring additional habilitation. However, vestibular testing is not routine in the pediatric population, and vestibular habilitation is seldo considered for CCI. The long-term goals of this research program are to characterize the developmental impact of pediatric vestibular loss and to guide the development of rehabilitative tools that minimize, or reverse, this impact. As a first step, the objectives in the present proposl are to characterize vestibular function in CCI, and investigate the effect of vestibular loss on static (head stable) and dynamic (head in motion) visual acuity as well as gross motor development in these children. The central hypothesis is that static visual acuity (SVA), dynamic visual acuity (DVA), and gross motor development are degraded in CCI with vestibular loss. This hypothesis is based on research in adults with vestibular loss, who experience reduced visual acuity with standing, walking and head movement, which impairs activities of daily living. The rationale for the proposed research is that reduced visual acuity, especially in the classroom, may impair academic success in CCI. Preliminary data obtained in our lab suggests that gross motor development and visual acuity are reduced in CCI with vestibular loss. Two specific aims will be addressed in this proposal: 1) we will characterize vestibular loss and its relationship with gross motor development and DVA in CCI, and 2) we will evaluate the effect of vestibular loss on SVA in these children. We will focus on CCI, who have increased risk of vestibular loss due to the etiology and magnitude of their hearing loss and the process of implantation. The likelihood of vestibular loss is 50% in CCI, allowing for a sufficient sample siz to address the research questions. CCI with normal vestibular function (matched in degree of hearing loss to the CCI with vestibular loss) will serve as controls. This provides a population of children where consequences of vestibular loss can be better studied. In Aim 1, a new approach for assessing semicircular-canal function that has been developed for use in adults will be evaluated in children. Additionally, the relationship between severity of vestibular loss, gross motor performance and DVA will be investigated. In Aim 2, SVA will be assessed with the head fixed in a chin rest and with the head held naturally in a stable position, using 3 levels of visua target complexity in order to determine the contribution of vestibular loss on SVA. Because hearing loss alone can play a significant role in speech, language, cognition, and reading, understanding the additional impact of vestibular loss is essential. This work will provide knowledge regarding the prevalence of vestibular loss and the extent to which vestibular loss affects visual acuity in CCI. This will further advance our understanding of the natural compensation process of vestibular loss in CCI and lead to further investigations regarding the identification, implications, and habilitation of pediatric vestibular loss.